Rheometer / Rubber Process Analyzer
Advanced RPA for rubber compound testing with high speed DAQ, programmable die gap / force, pneumatic cooling, variable oscillation amplitude from ±0.0001—360° (±0.0014—5000% Strain) and frequency from 0.001 Hz to 100 Hz
The D-RPA 3000 is a dynamic rubber process analyzer designed to measure the viscoelastic properties of elastomeric and rubber compounds before, during and after cure. The acquired data gives exact information about the processability, the cure characteristics, the cure speed, as well as the behavior of the compound after it cures.
The D-RPA 3000 fulfills the complete range of rheometer test requirements: polymers, raw materials, basic, finished, and cured compounds can be characterized. Cure properties, cure characteristics and processability can be determined and evaluated.
The high flexibility of the D-RPA 3000 allows the user to program and execute arbitrary test sequences with the MonControl Analysis Software. Isothermal tests, non-isothermal tests, amplitude sweeps, frequency sweeps, temperature sweeps, shear rate sweeps, relaxations, retardations, hysteresis and tensile tests can be executed in any combination or sequence.
The D-RPA 3000 is equipped with a two-channel compressed air cooling system. This cooling system controls upper and lower dies separately, making it possible to cool down the sample rapidly. The cooling system can be operated with normal compressed air or with chilled compressed air.
The testing instrument consists of the rheometer, computer with MonControl analysis software, wide-screen monitor, keyboard, mouse and printer.
Because of the very high measuring precision of the D-RPA 3000, small variations of the ingredients can be detected in the test result data, which simplifies quality control and the development of new rubber compounds.
Due to the rugged construction of the D-RPA 3000, it can be used for quality control purposes in the laboratory or directly in the production area.
- Lower costs per test
- Faster batch release - with only one test all essential physical characteristics can be determined. (Quality control data, cure characteristics and properties can be determined with only one test of one test sample)
- Significant reduction of scrap and rework
- Efficiency increase of the production process
- Faster and significantly simplified development cycles
- Intuitive, simple operation of the MonControl Analysis Software
- No separate sample preparation necessary
Description of Operation
The test chamber is equipped with a pneumatic closing system which moves the upper test chamber half to the lower test chamber half. The two test chamber halves form a closed, bi-conical system. This ensures a constant shear rate which is independent of the die radius in the sample.
The default closing force is 11.6 kN at 4.5 bar air pressure. This completely closes the test chamber and keeps the test sample under pressure during the test / cure. The opening of the test chamber is possible at any time.
To protect the user, a safety shield is lowered before the test chamber is closed. Between tests the chamber can manually be closed in a standby mode. A delay time for opening the safety shield can be configured in the software. Furthermore there is a port on the back of the rheometer for suction of waste gas produced during testing.
Temperature control of both electrically heated test dies is made by the MonControl Analysis Software with a separate control system for each test die. Temperature measurement is performed by PT 100 resistance thermometers. Both dies are heated by a heating film with spiral windings. This design ensures temperature uniformity throughout the dies. Both chambers are cooled separately by a PID-controlled forced air cooling system. The cooling system can be freely programmed in the test definition to cool during test sequences to conduct any friction heat from the sample.
The rubber mixture sample is tested under sinusoidal torsion generated by the lower test chamber during the test. The D-RPA 3000 can vary oscillation amplitude from ±0.0001° to 360° and frequency from 0.001 Hz to 100 Hz. This movement is generated by a high precision torque motor system with integrated ceramic bearings and precision path recording. The motor is mounted directly to the shaft of the lower die. The motor is software controlled and regulated by a corresponding high-resolution motor controller with overload protection.
The reaction torque is measured by a high-resolution strain gauge transducer mounted above the upper test die. This transducer can also measure the pressure in the test chamber.
Control and data acquisition is performed via the connected computer using MonControl analysis software. For the storage and analysis of the determined measurement data, a modern SQL database structure is provided. Over 1,500 time and torque characteristics are available for the selection of test results from the viscous and elastic portions of the mixture.
For the best possible determination of all relevant test parameters the D-RPA 3000 is equipped with a large variety of test methods, test parameters as well as calculation and evaluation options.
|Torque||Elastic modulus S‘
Viscous Modulus S‘‘
|Scorch-times||Normal force measurement P (optional)|
The following measurands can be determined:
- Shear modulus G’ and G’’
- Complex shear modulus G*
- Torque S’ and S’
- Complex torque S*
- Dynamic real viscosity n‘
- Dynamic imaginary viscosity n‘‘
- Dynamic complex viscosity n*
- Loss angle d
- Pressure (optional)
- Modulus under extension/compression E*, E’, E’’
- Compliance under extension/compression D*, D’, D’’
- Spring rate Ks, Kc, Kp
- Damping coefficient C
Oscillation as a function of the frequency
Modulation with a constant speed amplitude
Modulation with a superimposed shear
Further derived measurements
- Modulus under extension/compression
- Compliance under extension/compression
MonControl Analysis Software
MonControl Analysis Software enables the user to configure, combine and execute the respective tests. After inserting the test sample the actual test sequence is executed fully automatic without any intervention of the operator. The D-RPA 3000 in combination with the MonControl Analyses Software offers a huge variety of test parameters, which makes it possible to determine the sample properties in a very wide range.
The following test parameters are freely definable:
- Oscillation frequency
- Oscillation amplitude
- Sampling rate
- Number of measuring cycles
- Pressure (optional)
- Die gap (optional)
The following test programs are available with the D-RPA 3000:
- Amplitude Sweep:
The deflection angle (Amplitude) is changed during test at a predefined frequency and temperature.
- Frequency Sweep: The frequency of the oscillation is changed during test at a predefined amplitude and temperature.
- Temperature Sweep: The temperature of the test chamber is changed during test at a predefined amplitude and frequency.
- Shear rate Sweep: Changing of the shear rate during the examination. The shear rate sweep represents a sequence of different retardation cycles.
- Relaxation: Relaxation describes the unstressing after a strain. Stable physical systems return to an outer perturbation over relaxation processes nearly into their ground state. The relaxation time is a time constant which is characteristic for the given relaxation process. If the quantity f(t) of the relaxations follows an exponential rule: f(t) = exp( - t / t) * f(t = 0) then t is the accompanying relaxation time.
- Retardation: Examination of the fatigue behavior of a material under a constant load. Besides the elastic deformation the material experiences a time-dependent reversible (viscoelastic) and an irreversible (plastic) deformation. At the transition to the plastic condition the tension remains constant in the material. The force-time graph describes an e-function. If the stress is too high it comes time-dependently to a break of the material.
- Hysteresis: The change of the viscosity under influence of one constant shear gradient, depending on the duration of the influence. With increasing duration of the influence by the shear force the hysteresis effect is increasingly irreversible.
- Tensile tests: A material identification value which indicates the lasting prolongation of the
break related to the initial measuring length.
- many more test programs
Features a combined torque / forced transducer to measure torque as well as the pressure within the test chamber. Before each test, the transducer and amplifier is balanced automatically. The system also includes a second channel amplifier system for real-time simultaneous measurements of torque and normal force.
With this option, that cavity pressure can also be controlled either to a pre-programmed or to an on-line calculated pressure level. Therefore the closing force as well as the die gap are designed as a variable, independent axis, so that the cavity pressure can be precisely controlled. This system is especially suitable for test sequences that include curing as well as a cool-down of the sample for a dynamical mechanical analyses. Therefore the system can be utilized to compensate material shrinkage as well as to avoid any slippage in the test chamber. This technology is worldwide patented by MonTech.
High speed data acquisition system
The high speed DAQ option offer unique result stream resolution as well as an ultimate level of precision for torque as well as the motor position signal. Therefore both channels are sampled and processed simultaneously with a resolution of 24Bit at a data rate of 180KHz. All data streams are provided on the PC and calculated on-line in a Real-time kernel. Also it is possible to save the raw data streams to the PC memory. This makes the system especially suitable for FT-Rheology purposes.
MCool 10 Chilled Air Cooling
This system uses chilled air to further enhance the performance of the rheometer by cooling the test chambers to as low as +8°C. This system is especially suitable for tests at or below room temperature and is highly recommended for dynamic testing on very soft rubbers, polymers and silicones. Only a compressed air supply with at least 4 Bars is required - there are no additional chillers or cooling liquids required. Performance of the cooling systems depends on supplied air. This technology is worldwide patented by MonTech.
MCool -40 Liquid Cooling
This cooling system is the ideal dynamic mechanical rheological testing system, able to run anything from sample curing down to glass transition testing as low as -40°C. This system works as an addition to the pneumatic cooling system. The chiller is started only if lower temperatures are required. The total heating system of the dies remains unchanged so that instruments equipped with this devices are absolutely comparable with any other Moving Die Rheometer. This technology is worldwide patented by MonTech.
Rheometer volume punch
For the exact production of test samples for rheometers, the R-VS 3000 sample cutter is an available option. This volume punch is used for rapid and accurate preparation of test specimens. The usage of a volume cutter is recommended because this ensures reliable and reproducible test results.
|International standards||ISO 6502 / ASTM D 5289 / ASTM D 6204 / ASTM D 6601 / DIN 53529|
|Test chamber||Bi-conical, closed system|
|Test chamber gap||0.45 mm nominal|
|Force measurement||Torque and force transducer attached to upper die|
|Closing system||Damped closed system, pneumatically with non-contact spring elevation system|
|Oscillation frequency||0.001 Hz - 100 Hz|
|Oscillation amplitude||Variable, ±0.0001—360° (±0.0014—5000% Strain)|
|Torque range||0.0001 to 235 dNm|
|Sample volume||approx. 4.5 cm³|
|Temperature control system||30°C to 232°C, precision +/- 0.03°C both microprocessor controlled
low-temperature cooling systems available
|Temperature check system||Recordings of the temperature gradient on the screen, microprocessor monitored|
|Units of measure||Torque (dNm, lbf•in, kgf•cm)
Shear modulus (Pa, dynes/cm², psi)
Dynamic viscosity (Pa s)
Temperature (°C, °F)
Pressure (bar, kg per cm²)
Time (min - min / min - sec)
Frequency (Hz, cpm)
Shear rate (1/s, rad/s)
|Pneumatics||min 4.5 Bar|
|Sub tests||Amplitude Sweep, Frequency Sweep, Temperature Sweep, Shear rate Sweep, Relaxation, Retardation, Hysteresis, Tension test|
|Electrical||Single phase 220 V - 230 V, 5 Amps|
|Connection for dust / vapor extraction||100mm dia|